Volumetric ultrasound scanning of the breast has been proposed as a complementary modality for breast cancer screening as described, for example, in the commonly assigned US 2003/007598A1 published Jan. 9, 2003, which is incorporated by reference herein. Whereas a conventional two-dimensional x-ray mammogram only detects a summation of the x-ray opacity of individual slices of breast tissue over the entire breast, ultrasound can separately detect the sonographic properties of individual slices of breast tissue, and therefore may allow detection of breast lesions where x-ray mammography alone fails. Another well-known shortcoming of x-ray mammography practice is found in the case of dense-breasted women, including patients with high content of fibroglandular tissues in their breasts. Because fibroglandular tissues have higher x-ray absorption than the surrounding fatty tissues, portions of breasts with high fibroglandular tissue content are not well penetrated by x-rays and thus the resulting mammograms contain reduced information in areas where fibroglandular tissues reside.
The commonly assigned WO 2004/030523A2 published on Apr. 15, 2004, which is incorporated by reference herein, describes a full-field breast ultrasound (FFBU) scanning apparatus that compresses a breast along view plane such as the craniocaudal (CC) plane, the mediolateral oblique (MLO) plane, etc., and ultrasonically scans the breast. A scanning surface comprises an at least partially conformable, substantially taut membrane or film sheet compressing one side of the breast. The other side of the breast is compressed by a compression plate with an inflatable air bladder. A transducer translation mechanism holds a transducer surface against an opposite side of the film sheet while translating the transducer thereacross to scan the breast. An irrigation system automatically maintains a continuous supply of coupling agent at an interface between the transducer surface and the film sheet as the transducer is translated.
The operation of the scanning apparatus described in WO 2004/030523A2, supra, depends at least in part on the “pendulous” properties of the breast, that is, the ability of the breast to extend away from the chest wall onto the scanning surface for compression along the axial plane (for CC scan), sagittal plane (for lateral scan), or other anti-coronal plane lying between the axial and sagittal planes (e.g., for MLO scan). As used herein, the term anti-coronal plane refers to a plane that lies generally perpendicular to the coronal plane. As with conventional x-ray mammography, the presumption is made that most breasts will have such pendulous properties. While effective for a large portion of the population, problems arise for patients having smaller breasts without pendulous properties, because much of the diagnostically relevant breast tissue cannot extend outward over the scanning surface by a sufficient amount. Moreover, even for patients with pendulous breasts, there can be difficulty in imaging the tissue near the chest wall that does not extend onto the scanning surface.
One important quality a breast ultrasound scanning apparatus is ease of mechanical control and manipulation. Generally speaking, acquiring volumetric ultrasonic breast scans can be a highly patient-specific process, not only in view of the wide variety of breast sizes, shapes, and densities, but also in view of the wide variety of different patient body shapes near and around the breast area (e.g., shoulder contours, sternum contours, ribs contours, etc.) A scanning apparatus that is versatile and easily adaptable to the particular patient being scanned can therefore facilitate optimal acquisition of ultrasonic views of the breast volume. Moreover, ease of use can also positively affect the salability and commercial success of the scanning apparatus.
In addition to being able to perform thorough and high-quality volumetric scans of breasts having different sizes, shapes, and densities, which requires substantial scanner versatility, another important quality in a breast scanning system is its amenability to at least some degree of clinical systemization and/or standardization. For example, it would be desirable to have the same breast scanned the same way in different years to provide meaningful year-over-year comparisons, even where the ultrasound scans are performed by different technicians on different scanning units. Likewise, it would be desirable to provide a system that allows for easy comparisons of tissue structures in different patients having similarly-formed breasts, to foster more universally applicable radiologist interpretation skills, to provide for the development of better training materials, and/or to provide for the development of image databases for training automated or semi-automated computer-aided diagnosis (CAD) systems.
Accordingly, it would be desirable to provide a breast ultrasound scanning system that is capable of accommodating small, non-pendulous breasts as well as pendulous breasts.
It would be further desirable to provide a breast ultrasound scanning apparatus that can achieve high-quality ultrasound imaging even near the chest wall of the patient.
It would be even further desirable to provide such a breast ultrasound scanning apparatus that is comfortable for the patient, has a cost-efficient patient throughput rate, and that is cost-efficient to own even for smaller medical clinics.
It would be still further desirable to provide such a breast ultrasound scanning apparatus that is versatile, able to accommodate patients of different heights and/or disabilities, and capable of facilitating individualized scanning procedures.
It would be even further desirable to provide methods for facilitating at least some degree of standardization in the way breasts of different sizes, shapes, and/or densities are scanned using such breast ultrasound scanning apparatus.